Refrigeration system defrosting means

ABSTRACT

A vertically extending evaporator such as used in a side-by-side refrigerator-freezer having a U-shaped defrost heater including legs extending upwardly adjacent the opposite sides of the evaporator and a bight portion adjacent the bottom of the evaporator. The refrigeration fluid header is disposed adjacent the top of the evaporator and the bight portion of the defrost heater functions to melt ice accumulation in a drain pan disposed subjacent the evaporator.

United States Patent Tobey REFRIGERATION SYSTEM DEF ROSTIN G MEANS [72] inventor: Raymond E. Tobey, Evansville, Ind. [73] Assignee: Whirlpool Corporation [22] Filed: May 10, 1971 [21] Appl. No.: 141,478

[52] US. Cl. ..62/276, 62/ 151, 62/285 [51] Int. Cl ..F25d 21/06 [58] Field of Search ..62/275, 276, 151, 156

[56] References Cited UNITED STATES PATENTS 3,394,559 7/ l 968 Jones ..62/276 3,436,931 4/1969 Gilbard ..62/276 3,465,534 9/1969 Sutton ..62/151 3,590,596 7/1971 Johnson ..62/276 51 Aug. 15, 1972 Primary Examiner-William J. Wye

Attorney-James S. Nettleton, Thomas E. Turcotte, Donald W. Thomas, Gene A. -Heth, Franklin C. Hatter, Anthony Niewyk, Robert L. Judd, Edward A.

Ketterer and Hofgren, Wegner, Allen, Stellman & Mc- Cord ABSTRACT A vertically extending evaporator such as used in a side-by-side refrigerator-freezer having a U-shaped defrost heater including legs extending upwardly adjacent the opposite sides of the evaporator and a bight portion adjacent the bottom of the evaporator. The refrigeration fluid header is disposed adjacent the top of the evaporator and the bight portion of the defrost heater functions to melt ice accumulation in a drain pan disposed subjacent the evaporator.

12 Claims, 3 Drawing Figures FIGS INVENTOR- RAYMOND E. TOBEY MI QM JWIQIWKM.

ATTORNEYS.

Patented Aug. 15, 1972 FIG] REFRIGERATION SYSTEM DEFROSTING MEANS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to refrigeration systems and in particular to defrost heaters for use in defrosting an evaporator of a refrigerator-freezer.

2. Description of the Prior Art In conventional side-by-side refrigerator-freezers, the defrost heater has comprised a serpentine heater extending from the top of the evaporator downwardly to adjacent the bottom of the evaporator. Such heater constructions are relatively expensive and difficult to service. In particular, such heater constructions are difficult and expensive to replace in the field.

In addition, in the conventional vertical evaporator construction of such side-by-side refrigerator-freezers, a separate drain pan defrost heater is required. In such prior art systems, the header for the refrigerant fluid is disposed at the lower end of the evaporator presenting frost accumulation problems and making difficult the removal of ice from the drain pan.

In other types of evaporators, such as horizontally extending evaporators, defrost heaters have been developed having portions extending below the evaporator and adjacent the opposite ends of the evaporator. In such conventional horizontal evaporators, the header is disposed below the evaporator presenting the problems discussed above. Examples of prior art structures as discussed above are those shown in E. V. Dickson et al. U.S. Pat. No. 3,304,740 and Frank L. Stevens U.S. Pat. No. 3,359,751.

SUMMARY OF THE INVENTION The present invention comprehends an improved defrosting means for use in a refrigeration system having a vertical evaporator. Such a vertical evaporator has a height greater than the width thereof. The defrosting means defines a U-shaped heater having vertically extending legs disposed adjacent the opposite sides of the evaporator for defrosting the evaporator at the sides thereof. The defrost heater bight portion may have a length less than the length of the legs. The header of the refrigeration system is preferably disposed at the top of the evaporator whereby the bight portion of the defrost heater may effectively melt ice which may form in the drain pan disposed subjacent the bottom of the evaporator.

The legs of the defrost heater may extend between the end turns of the evaporator tube means. At least one side of the evaporator is defined by a side plate arranged to deflect the air being circulated in heat transfer association with the evaporator so as to direct a majority of the air upwardly along the side of the evaporator when the evaporator is substantially frostfree. When the side portion of the evaporator becomes frosted so as to impede the free air flow upwardly therealong, the impeded air flow is diverted to the portion of the evaporator between the sides thereof whereby extended operation of the evaporator may be obtained between defrosting operations.

The defrost heater is extremely simple and economical of construction and may be readily replaced in the field by virtue of the simple geometric configuration thereof. By virtue of the elimination of the conventional drip pan defrost heater, a further substantial saving in the refrigeration system is obtained while yet extended frost-free operation is provided.

BRIEF DESCRIPTION OF THE DRAWING 0 unit having a defrost means embodying the invention,

the doors of the unit being removed to facilitate illustration of the invention;

FIG. 2 is a perspective view of the evaporator and defrost means; and

FIG. 3 is an enlarged side elevation of the evaporator and defrost means.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as disclosed in the drawing, a refrigeration system generally designated 10 is shown to comprise an upright side-by side refrigerator-freezer unit defined by a cabinet 11 defining an above-freezing refrigeration space 12 and a below-freezing freezer space 13. Spaces 12 and 13 are separated by a wall 14 having a through air passage 15 in a lower portion thereof for conducting air from the refrigerator space 12 to an evaporator space 16 in which a fin and tube type evaporator 17 is disposed. Air from freezer space 13 is introduced to space 16 through a grille 18, as shown in FIG. 1. Air is circulated in heat transfer association with evaporator 17 through space 16 by suitable air moving means herein illustratively comprising a fan 19 disposed within a suitable shroud 20 leading upwardly from the top of evaporator space 16 to a discharge duct 21 having a discharge opening 22 leading to refrigeration space 12 and a discharge opening 23 leading to freezer space 13.

As discussed briefly above, the invention comprehends the provision of an improved defrost heater generally designated 24 for periodically defrosting the evaporator. As best seen in FIG. 2, the evaporator 17 comprises a vertical evaporator having a height substantially greater than the width thereof and includes a tube portion 25 for conducting refrigerant fluid therethrough and a plurality of fins 26 in thermal transfer association with the tube means 25 for improved heat transfer with the air flowed upwardly past the evaporator by fan 19.

The refrigeration systems utilizing such evaporators are well known to those skilled in the art and require no further description herein, it being understood that the refrigeration system includes conventional compressor and condenser means. Tube means 25 includes a plurality of end turns 27 at the opposite sides 28 and 29 of the evaporator. The end turns extend into a flow passage 30 outwardly of evaporator sides 28 and 29. The evaporator is defined by side plates 31 at sides 28 and 29, as shown in FIG. 3. The lower portion 32 of the right side plate 31 extends across the path of air flow from air passage 15 so as to deflect the air upwardly through space 30 at the right side 28 of the evaporator. As seen in FIGS. 2 and 3, the tube end turns 27 extend outwardly beyond the end plates 31 to be in the path of air flow of the portion of the circulated air flowed upwardly through space 30. The remainder of the air being circulated by fan 19 passes downwardly to the bottom of the evaporator and turns upwardly between sides 28 and 29 to fan 19, with the air being cooled by the heat exchange association thereof with fins 26.

When the evaporator is in a substantially frost-free condition, a majority of the air from refrigerator space 12 flows upwardly through space 30 as discussed above. Thus, frosting of the evaporator between sides 28 and 29 is effectively retarded. When sufficient frost collects on the end turns 27 to impede the air flow upwardly through passage 30, the fan may draw the air upwardly through the evaporator between sides 28 and 29 to continue the air refrigerating operation. Eventually, when the evaporator between sides 28 and 29 also becomes frosted, the cooling operation is interrupted to effect a defrosting operation in the conventional manner.

As discussed above, the defrost heater 24 comprises a simple U-shaped heating element providing an improved defrost functioning. Thus, heater 24'includes upright legs 33 and 34 spaced apart to be juxtaposed to the opposite sides 28 and 29 of the evaporator. As best seen in FIG. 3, evaporator end turns 27 include portions spaced horizontally apart. The defrost heater legs 33 and 34 are disposed to extend between the horizontally spaced end turns, as shown in FIG. 3, for improved defrosting association therewith.

Heater 24 further includes a lowermost transversely extending bight portion 35 extending subjacent the bottom of the evaporator and above a subjacent drip pan 36. As shown in FIGS. 2 and 3, the bight portion 35 may be offset rearwardly of the evaporator by connecting portions 37. As shown, legs 33 and 34 have a length greater than the length of the bight portion 35 generally corresponding to the height and width relationship of the evaporator 17. The upper end of legs 33 and 34 may terminate adjacent the top of the evaporator.

The refrigeration system header 38 is preferably mounted at the top of the evaporator, as shown in FIGS. 2 and 3, facilitating the melting of any ice which may form at drip pan 36 by the defrost portion 35 which may be in direct radiant association with the drip pan, as shown in FIG. 3.

A metal plate 39 may be disposed as necessary at each of the opposite sides of the evaporator outwardly of the end turns 27 to prevent excessive heating of the dividing wall 14 and cabinet 11 by the defrost heater during the energization thereof.

Thus, the simplified defrost heater 24 provides an improved construction and refrigeration system performance in a simple and economical manner. The relatively moist air from the above-freezing refrigeration space 12 is prevented from frosting the main body of the evaporator by the directing of the majority of the air flow therefrom through the end turn spaces 30 during the initial phase of the refrigeration operation. When the end turn spaces become sufficiently frosted to impede this bypass air flow, refrigeration operation is continued by the automatic redirecting of the majority of the air flow through the mid-portion of the evaporator. Not only is the cost of the apparatus reduced by the simplified U-shaped configuration of the defrost heater 24, but further, the cost is minimized by eliminating the need for additional heaters, such as the drip pan heater required in conventional refrigeration systems.

The present invention comprehends the flow of air from freezer compartment 13 through the grille 18 to the mid-portion of the evaporator 17 for maximum cooling thereof. It is only when the spaces 30 are sufficiently frosted to impede the flow of above-freezing air from refrigeration space 12 that the freezer air is commingled with a substantial volume of above-freezing temperature air in the evaporator so that improved low temperature cooling of the freezer space 13 is provided.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Having described the invention, the embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a refrigerator-freezer having an above-freezing space and a below-freezing space, a vertical evaporator having a height greater than the width thereof and means for circulating air to be cooled from adjacent the bottom of the evaporator, upwardly past the evaporator in heat transfer association therewith, and from a discharge adjacent an upper portion of the evaporator, defrosting means comprising:

a U-shaped heater having vertically extending, spaced legs disposed adjacent opposite sides of the evaporator for defrosting the evaporator at the evaporator at the opposite side thereof, and

a bight portion extending transversely between the lower ends of the legs adjacent the bottom of the evaporator for defrosting the evaporator between said sides, the length of said bight portion being less than the length of said legs.

2. The refrigerator-freezer defrosting means of claim 1 further including a header for refrigerant fluid circulated through the evaporator disposed adjacent the upper portion of the evaporator.

3. The refrigerator-freezer defrosting means of claim 1 further including means for directing circulated air from the above-freezing space upwardly along the sides of the evaporator and circulated air from the belowfreezing space upwardly past the evaporator between said sides.

4. The refrigerator-freezer defrosting means of claim 3 wherein said air directing means comprises means for directing the majority of said above-freezing space air upwardly along said evaporator sides when the evaporator is substantially frost-free and causing the majority of said above-freezing space air to be directed upwardly past the evaporator between said sides when the sides of the evaporator become frosted.

5. The refrigerator-freezer defrosting means of claim 1 wherein the evaporator comprises a tube and fin evaporator having tube end turns at the sides of the evaporator, said defrost heater legs being juxtaposed to said end turns to remove frost accumulation therefrom.

6. The refrigerator-freezer defrosting means of claim 5 wherein said end turns include horizontally spaced turns and said defrost heater legs extend between said horizontally spaced turns.

7. The refrigerator-freezer defrosting means of claim 1 further including a drain pan subjacent the evaporator, said bight portion of the defrost heater being disposed for effectively melting ice accumulation therein.

8. The refrigerator-freezer defrosting means of claim 1 further including a header for refrigerant fluid circulated through the evaporator disposed adjacent the upper portion of the evaporator above the level of the top of said defrost heater legs.

9. The refrigerator-freezer defrosting means of claim 3 wherein said evaporator includes a side plate extending to adjacent the bottom of the evaporator and defining means for deflecting said above-freezing space air such that a majority of said above-freezing space air is directed upwardly along the sides of the evaporator when the evaporator is substantially frost-free.

10. A refrigeration system structure comprising:

an evaporator having a height substantially greater than the width thereof; a header adjacent the top of the evaporator;

a drain pan adjacent the bottom of the evaporator;

means for circulating air upwardly in heat exchange association with the evaporator; and

U-shaped heater means having a bight portion adjacent the bottom of the evaporator for defrosting the evaporator and melting ice accumulation in the drain pan.

11. The refrigeration system structure of claim 10 wherein said bight portion of said heater means comprises a horizontal heater means extending between the bottom of the evaporator and above the drain pan.

12. The refrigeration system structure of claim 10 wherein said bight portion of said heater means extends substantially the full length of the drain pan. 

1. In a refrigerator-freezer having an above-freezing space and a below-freezing space, a vertical evaporator having a height greater than the width thereof and means for circulating air to be cooled from adjacent the bottom of the evaPorator, upwardly past the evaporator in heat transfer association therewith, and from a discharge adjacent an upper portion of the evaporator, defrosting means comprising: a U-shaped heater having vertically extending, spaced legs disposed adjacent opposite sides of the evaporator for defrosting the evaporator at the evaporator at the opposite side thereof, and a bight portion extending transversely between the lower ends of the legs adjacent the bottom of the evaporator for defrosting the evaporator between said sides, the length of said bight portion being less than the length of said legs.
 2. The refrigerator-freezer defrosting means of claim 1 further including a header for refrigerant fluid circulated through the evaporator disposed adjacent the upper portion of the evaporator.
 3. The refrigerator-freezer defrosting means of claim 1 further including means for directing circulated air from the above-freezing space upwardly along the sides of the evaporator and circulated air from the below-freezing space upwardly past the evaporator between said sides.
 4. The refrigerator-freezer defrosting means of claim 3 wherein said air directing means comprises means for directing the majority of said above-freezing space air upwardly along said evaporator sides when the evaporator is substantially frost-free and causing the majority of said above-freezing space air to be directed upwardly past the evaporator between said sides when the sides of the evaporator become frosted.
 5. The refrigerator-freezer defrosting means of claim 1 wherein the evaporator comprises a tube and fin evaporator having tube end turns at the sides of the evaporator, said defrost heater legs being juxtaposed to said end turns to remove frost accumulation therefrom.
 6. The refrigerator-freezer defrosting means of claim 5 wherein said end turns include horizontally spaced turns and said defrost heater legs extend between said horizontally spaced turns.
 7. The refrigerator-freezer defrosting means of claim 1 further including a drain pan subjacent the evaporator, said bight portion of the defrost heater being disposed for effectively melting ice accumulation therein.
 8. The refrigerator-freezer defrosting means of claim 1 further including a header for refrigerant fluid circulated through the evaporator disposed adjacent the upper portion of the evaporator above the level of the top of said defrost heater legs.
 9. The refrigerator-freezer defrosting means of claim 3 wherein said evaporator includes a side plate extending to adjacent the bottom of the evaporator and defining means for deflecting said above-freezing space air such that a majority of said above-freezing space air is directed upwardly along the sides of the evaporator when the evaporator is substantially frost-free.
 10. A refrigeration system structure comprising: an evaporator having a height substantially greater than the width thereof; a header adjacent the top of the evaporator; a drain pan adjacent the bottom of the evaporator; means for circulating air upwardly in heat exchange association with the evaporator; and U-shaped heater means having a bight portion adjacent the bottom of the evaporator for defrosting the evaporator and melting ice accumulation in the drain pan.
 11. The refrigeration system structure of claim 10 wherein said bight portion of said heater means comprises a horizontal heater means extending between the bottom of the evaporator and above the drain pan.
 12. The refrigeration system structure of claim 10 wherein said bight portion of said heater means extends substantially the full length of the drain pan. 